After successful testing, Bertha prepares to tweet her way to Elliott Bay

SEATTLE – It won’t be long before Bertha, the world’s largest-diameter tunneling machine, starts digging the State Route 99 tunnel beneath downtown Seattle. But first she faces a long journey from her manufacturing plant in Osaka, Japan, to the waters of Elliott Bay.

Crews in Japan began disassembling the five-story-tall, $80 million machine last week. By mid-month, Bertha – which is owned by Seattle Tunnel Partners (STP), the Washington State Department of Transportation’s contractor for the project – will be aboard the Jumbo Fairpartner in 41 pieces. The ship will leave Japan in mid-March and arrive in Seattle later this month, if the weather cooperates.

“We’re entering an exciting stage of this project,” said Linea Laird, WSDOT’s administrator for the Alaskan Way Viaduct Replacement Program. “While we have a lot of work to do once Bertha arrives, we can’t wait to introduce her to the people of Washington.”

Bertha, for which WSDOT launched a Twitter account in December, is looking forward to her boat ride. “Well, I’m in pieces here in Japan,” @BerthaDigsSR99 tweeted today. “Don’t worry, that’s part of the plan. I’m being loaded on a ship bound for Seattle. Leaving in mid-March!”

As Bertha’s owner, STP is responsible for ensuring she functions properly at all times. Accordingly, she’s been put through a succession of rigorous tests at the Sakai Works factory in Osaka, where manufacturer Hitachi Zosen Corporation built the machine. One of the tests revealed a problem with the machine’s main drive unit, and crews made appropriate repairs. Bertha has since passed all of her tests, and will officially become the property of STP once she’s tunneled approximately 1,000 feet without any issues.

“Construction is going well, both in Japan and in Seattle,” said Chris Dixon, Seattle Tunnel Partners project manager. “We’re on track to open the tunnel in late 2015.”

Crews in Seattle are about 80 percent finished with the pit where Bertha will start her journey. In addition to building the launch pit, crews are preparing the surrounding area for tunneling. That work includes strengthening the soil and building protected areas along the initial section of the tunnel route so crews can perform scheduled inspections of the machine before it begins tunneling beneath the city. Work is also under way near the north end of the Battery Street Tunnel to prepare the area where Bertha will emerge at the end of tunneling.

Bertha’s 41 pieces – the largest weighing up to 900 tons – are being loaded on a single ship. Once she arrives in Seattle, crews will unload the pieces and transport them a few hundred yards to the 80-foot-deep pit, where she will be reassembled and launched beneath downtown this summer.

WSDOT will host a presentation about Bertha’s arrival at 6 p.m. Thursday, March 7, at Milepost 31, the project’s information center in Pioneer Square. A 10-foot-long interactive model of the machine is on display at Milepost 31, and photos of the machine and construction in Seattle are also available.